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Source: \core\textures\Texture.js


    import BaseTexture from './BaseTexture';
import VideoBaseTexture from './VideoBaseTexture';
import TextureUvs from './TextureUvs';
import EventEmitter from 'eventemitter3';
import { Rectangle } from '../math';
import { TextureCache, BaseTextureCache, getResolutionOfUrl } from '../utils';

/**
 * A texture stores the information that represents an image or part of an image. It cannot be added
 * to the display list directly. Instead use it as the texture for a Sprite. If no frame is provided
 * then the whole image is used.
 *
 * You can directly create a texture from an image and then reuse it multiple times like this :
 *
 * ```js
 * let texture = PIXI.Texture.fromImage('assets/image.png');
 * let sprite1 = new PIXI.Sprite(texture);
 * let sprite2 = new PIXI.Sprite(texture);
 * ```
 *
 * Textures made from SVGs, loaded or not, cannot be used before the file finishes processing.
 * You can check for this by checking the sprite's _textureID property.
 * ```js
 * var texture = PIXI.Texture.fromImage('assets/image.svg');
 * var sprite1 = new PIXI.Sprite(texture);
 * //sprite1._textureID should not be undefined if the texture has finished processing the SVG file
 * ```
 * You can use a ticker or rAF to ensure your sprites load the finished textures after processing. See issue #3068.
 *
 * @class
 * @extends EventEmitter
 * @memberof PIXI
 */
export default class Texture extends EventEmitter
{
    /**
     * @param {PIXI.BaseTexture} baseTexture - The base texture source to create the texture from
     * @param {PIXI.Rectangle} [frame] - The rectangle frame of the texture to show
     * @param {PIXI.Rectangle} [orig] - The area of original texture
     * @param {PIXI.Rectangle} [trim] - Trimmed rectangle of original texture
     * @param {number} [rotate] - indicates how the texture was rotated by texture packer. See {@link PIXI.GroupD8}
     */
    constructor(baseTexture, frame, orig, trim, rotate)
    {
        super();

        /**
         * Does this Texture have any frame data assigned to it?
         *
         * @member {boolean}
         */
        this.noFrame = false;

        if (!frame)
        {
            this.noFrame = true;
            frame = new Rectangle(0, 0, 1, 1);
        }

        if (baseTexture instanceof Texture)
        {
            baseTexture = baseTexture.baseTexture;
        }

        /**
         * The base texture that this texture uses.
         *
         * @member {PIXI.BaseTexture}
         */
        this.baseTexture = baseTexture;

        /**
         * This is the area of the BaseTexture image to actually copy to the Canvas / WebGL when rendering,
         * irrespective of the actual frame size or placement (which can be influenced by trimmed texture atlases)
         *
         * @member {PIXI.Rectangle}
         */
        this._frame = frame;

        /**
         * This is the trimmed area of original texture, before it was put in atlas
         *
         * @member {PIXI.Rectangle}
         */
        this.trim = trim;

        /**
         * This will let the renderer know if the texture is valid. If it's not then it cannot be rendered.
         *
         * @member {boolean}
         */
        this.valid = false;

        /**
         * This will let a renderer know that a texture has been updated (used mainly for webGL uv updates)
         *
         * @member {boolean}
         */
        this.requiresUpdate = false;

        /**
         * The WebGL UV data cache.
         *
         * @member {PIXI.TextureUvs}
         * @private
         */
        this._uvs = null;

        /**
         * This is the area of original texture, before it was put in atlas
         *
         * @member {PIXI.Rectangle}
         */
        this.orig = orig || frame;// new Rectangle(0, 0, 1, 1);

        this._rotate = Number(rotate || 0);

        if (rotate === true)
        {
            // this is old texturepacker legacy, some games/libraries are passing "true" for rotated textures
            this._rotate = 2;
        }
        else if (this._rotate % 2 !== 0)
        {
            throw new Error('attempt to use diamond-shaped UVs. If you are sure, set rotation manually');
        }

        if (baseTexture.hasLoaded)
        {
            if (this.noFrame)
            {
                frame = new Rectangle(0, 0, baseTexture.width, baseTexture.height);

                // if there is no frame we should monitor for any base texture changes..
                baseTexture.on('update', this.onBaseTextureUpdated, this);
            }
            this.frame = frame;
        }
        else
        {
            baseTexture.once('loaded', this.onBaseTextureLoaded, this);
        }

        /**
         * Fired when the texture is updated. This happens if the frame or the baseTexture is updated.
         *
         * @event update
         * @memberof PIXI.Texture#
         * @protected
         */

        this._updateID = 0;

        /**
         * Extra field for extra plugins. May contain clamp settings and some matrices
         * @type {Object}
         */
        this.transform = null;

        /**
         * The id under which this Texture has been added to the texture cache. This is
         * automatically set in certain cases, but may not always be accurate, particularly if
         * the texture is in the cache under multiple ids.
         *
         * @member {string}
         */
        this.textureCacheId = null;
    }

    /**
     * Updates this texture on the gpu.
     *
     */
    update()
    {
        this.baseTexture.update();
    }

    /**
     * Called when the base texture is loaded
     *
     * @private
     * @param {PIXI.BaseTexture} baseTexture - The base texture.
     */
    onBaseTextureLoaded(baseTexture)
    {
        this._updateID++;

        // TODO this code looks confusing.. boo to abusing getters and setters!
        if (this.noFrame)
        {
            this.frame = new Rectangle(0, 0, baseTexture.width, baseTexture.height);
        }
        else
        {
            this.frame = this._frame;
        }

        this.baseTexture.on('update', this.onBaseTextureUpdated, this);
        this.emit('update', this);
    }

    /**
     * Called when the base texture is updated
     *
     * @private
     * @param {PIXI.BaseTexture} baseTexture - The base texture.
     */
    onBaseTextureUpdated(baseTexture)
    {
        this._updateID++;

        this._frame.width = baseTexture.width;
        this._frame.height = baseTexture.height;

        this.emit('update', this);
    }

    /**
     * Destroys this texture
     *
     * @param {boolean} [destroyBase=false] Whether to destroy the base texture as well
     */
    destroy(destroyBase)
    {
        if (this.baseTexture)
        {
            if (destroyBase)
            {
                // delete the texture if it exists in the texture cache..
                // this only needs to be removed if the base texture is actually destroyed too..
                if (TextureCache[this.baseTexture.imageUrl])
                {
                    delete TextureCache[this.baseTexture.imageUrl];
                }

                this.baseTexture.destroy();
            }

            this.baseTexture.off('update', this.onBaseTextureUpdated, this);
            this.baseTexture.off('loaded', this.onBaseTextureLoaded, this);

            this.baseTexture = null;
        }

        this._frame = null;
        this._uvs = null;
        this.trim = null;
        this.orig = null;
        this.textureCacheId = null;

        this.valid = false;

        for (const prop in TextureCache)
        {
            if (TextureCache[prop] === this)
            {
                delete TextureCache[prop];
            }
        }
    }

    /**
     * Creates a new texture object that acts the same as this one.
     *
     * @return {PIXI.Texture} The new texture
     */
    clone()
    {
        return new Texture(this.baseTexture, this.frame, this.orig, this.trim, this.rotate);
    }

    /**
     * Updates the internal WebGL UV cache.
     *
     * @protected
     */
    _updateUvs()
    {
        if (!this._uvs)
        {
            this._uvs = new TextureUvs();
        }

        this._uvs.set(this._frame, this.baseTexture, this.rotate);

        this._updateID++;
    }

    /**
     * Helper function that creates a Texture object from the given image url.
     * If the image is not in the texture cache it will be  created and loaded.
     *
     * @static
     * @param {string} imageUrl - The image url of the texture
     * @param {boolean} [crossorigin] - Whether requests should be treated as crossorigin
     * @param {number} [scaleMode=PIXI.settings.SCALE_MODE] - See {@link PIXI.SCALE_MODES} for possible values
     * @param {number} [sourceScale=(auto)] - Scale for the original image, used with SVG images.
     * @return {PIXI.Texture} The newly created texture
     */
    static fromImage(imageUrl, crossorigin, scaleMode, sourceScale)
    {
        let texture = TextureCache[imageUrl];

        if (!texture)
        {
            texture = new Texture(BaseTexture.fromImage(imageUrl, crossorigin, scaleMode, sourceScale));
            TextureCache[imageUrl] = texture;
        }

        return texture;
    }

    /**
     * Helper function that creates a sprite that will contain a texture from the TextureCache based on the frameId
     * The frame ids are created when a Texture packer file has been loaded
     *
     * @static
     * @param {string} frameId - The frame Id of the texture in the cache
     * @return {PIXI.Texture} The newly created texture
     */
    static fromFrame(frameId)
    {
        const texture = TextureCache[frameId];

        if (!texture)
        {
            throw new Error(`The frameId "${frameId}" does not exist in the texture cache`);
        }

        return texture;
    }

    /**
     * Helper function that creates a new Texture based on the given canvas element.
     *
     * @static
     * @param {HTMLCanvasElement} canvas - The canvas element source of the texture
     * @param {number} [scaleMode=PIXI.settings.SCALE_MODE] - See {@link PIXI.SCALE_MODES} for possible values
     * @return {PIXI.Texture} The newly created texture
     */
    static fromCanvas(canvas, scaleMode)
    {
        return new Texture(BaseTexture.fromCanvas(canvas, scaleMode));
    }

    /**
     * Helper function that creates a new Texture based on the given video element.
     *
     * @static
     * @param {HTMLVideoElement|string} video - The URL or actual element of the video
     * @param {number} [scaleMode=PIXI.settings.SCALE_MODE] - See {@link PIXI.SCALE_MODES} for possible values
     * @return {PIXI.Texture} The newly created texture
     */
    static fromVideo(video, scaleMode)
    {
        if (typeof video === 'string')
        {
            return Texture.fromVideoUrl(video, scaleMode);
        }

        return new Texture(VideoBaseTexture.fromVideo(video, scaleMode));
    }

    /**
     * Helper function that creates a new Texture based on the video url.
     *
     * @static
     * @param {string} videoUrl - URL of the video
     * @param {number} [scaleMode=PIXI.settings.SCALE_MODE] - See {@link PIXI.SCALE_MODES} for possible values
     * @return {PIXI.Texture} The newly created texture
     */
    static fromVideoUrl(videoUrl, scaleMode)
    {
        return new Texture(VideoBaseTexture.fromUrl(videoUrl, scaleMode));
    }

    /**
     * Helper function that creates a new Texture based on the source you provide.
     * The source can be - frame id, image url, video url, canvas element, video element, base texture
     *
     * @static
     * @param {number|string|HTMLImageElement|HTMLCanvasElement|HTMLVideoElement|PIXI.BaseTexture}
     *        source - Source to create texture from
     * @return {PIXI.Texture} The newly created texture
     */
    static from(source)
    {
        // TODO auto detect cross origin..
        // TODO pass in scale mode?
        if (typeof source === 'string')
        {
            const texture = TextureCache[source];

            if (!texture)
            {
                // check if its a video..
                const isVideo = source.match(/\.(mp4|webm|ogg|h264|avi|mov)$/) !== null;

                if (isVideo)
                {
                    return Texture.fromVideoUrl(source);
                }

                return Texture.fromImage(source);
            }

            return texture;
        }
        else if (source instanceof HTMLImageElement)
        {
            return new Texture(BaseTexture.from(source));
        }
        else if (source instanceof HTMLCanvasElement)
        {
            return Texture.fromCanvas(source);
        }
        else if (source instanceof HTMLVideoElement)
        {
            return Texture.fromVideo(source);
        }
        else if (source instanceof BaseTexture)
        {
            return new Texture(source);
        }

        // lets assume its a texture!
        return source;
    }

    /**
     * Create a texture from a source and add to the cache.
     *
     * @static
     * @param {HTMLImageElement|HTMLCanvasElement} source - The input source.
     * @param {String} imageUrl - File name of texture, for cache and resolving resolution.
     * @param {String} [name] - Human readible name for the texture cache. If no name is
     *        specified, only `imageUrl` will be used as the cache ID.
     * @return {PIXI.Texture} Output texture
     */
    static fromLoader(source, imageUrl, name)
    {
        const baseTexture = new BaseTexture(source, undefined, getResolutionOfUrl(imageUrl));
        const texture = new Texture(baseTexture);

        baseTexture.imageUrl = imageUrl;

        // No name, use imageUrl instead
        if (!name)
        {
            name = imageUrl;
        }

        // lets also add the frame to pixi's global cache for fromFrame and fromImage fucntions
        BaseTextureCache[name] = baseTexture;
        TextureCache[name] = texture;
        texture.textureCacheId = name;

        // also add references by url if they are different.
        if (name !== imageUrl)
        {
            BaseTextureCache[imageUrl] = baseTexture;
            TextureCache[imageUrl] = texture;
        }

        return texture;
    }

    /**
     * Adds a texture to the global TextureCache. This cache is shared across the whole PIXI object.
     *
     * @static
     * @param {PIXI.Texture} texture - The Texture to add to the cache.
     * @param {string} id - The id that the texture will be stored against.
     */
    static addTextureToCache(texture, id)
    {
        if (!texture.textureCacheId)
        {
            texture.textureCacheId = id;
        }
        TextureCache[id] = texture;
    }

    /**
     * Remove a texture from the global TextureCache.
     *
     * @static
     * @param {string} id - The id of the texture to be removed
     * @return {PIXI.Texture} The texture that was removed
     */
    static removeTextureFromCache(id)
    {
        const texture = TextureCache[id];

        delete TextureCache[id];
        delete BaseTextureCache[id];

        return texture;
    }

    /**
     * The frame specifies the region of the base texture that this texture uses.
     *
     * @member {PIXI.Rectangle}
     */
    get frame()
    {
        return this._frame;
    }

    set frame(frame) // eslint-disable-line require-jsdoc
    {
        this._frame = frame;

        this.noFrame = false;

        if (frame.x + frame.width > this.baseTexture.width || frame.y + frame.height > this.baseTexture.height)
        {
            throw new Error('Texture Error: frame does not fit inside the base Texture dimensions: '
                + `X: ${frame.x} + ${frame.width} > ${this.baseTexture.width} `
                + `Y: ${frame.y} + ${frame.height} > ${this.baseTexture.height}`);
        }

        // this.valid = frame && frame.width && frame.height && this.baseTexture.source && this.baseTexture.hasLoaded;
        this.valid = frame && frame.width && frame.height && this.baseTexture.hasLoaded;

        if (!this.trim && !this.rotate)
        {
            this.orig = frame;
        }

        if (this.valid)
        {
            this._updateUvs();
        }
    }

    /**
     * Indicates whether the texture is rotated inside the atlas
     * set to 2 to compensate for texture packer rotation
     * set to 6 to compensate for spine packer rotation
     * can be used to rotate or mirror sprites
     * See {@link PIXI.GroupD8} for explanation
     *
     * @member {number}
     */
    get rotate()
    {
        return this._rotate;
    }

    set rotate(rotate) // eslint-disable-line require-jsdoc
    {
        this._rotate = rotate;
        if (this.valid)
        {
            this._updateUvs();
        }
    }

    /**
     * The width of the Texture in pixels.
     *
     * @member {number}
     */
    get width()
    {
        return this.orig.width;
    }

    /**
     * The height of the Texture in pixels.
     *
     * @member {number}
     */
    get height()
    {
        return this.orig.height;
    }
}

function createWhiteTexture()
{
    const canvas = document.createElement('canvas');

    canvas.width = 10;
    canvas.height = 10;

    const context = canvas.getContext('2d');

    context.fillStyle = 'white';
    context.fillRect(0, 0, 10, 10);

    return new Texture(new BaseTexture(canvas));
}

function removeAllHandlers(tex)
{
    tex.destroy = function _emptyDestroy() { /* empty */ };
    tex.on = function _emptyOn() { /* empty */ };
    tex.once = function _emptyOnce() { /* empty */ };
    tex.emit = function _emptyEmit() { /* empty */ };
}

/**
 * An empty texture, used often to not have to create multiple empty textures.
 * Can not be destroyed.
 *
 * @static
 * @constant
 */
Texture.EMPTY = new Texture(new BaseTexture());
removeAllHandlers(Texture.EMPTY);
removeAllHandlers(Texture.EMPTY.baseTexture);

/**
 * A white texture of 10x10 size, used for graphics and other things
 * Can not be destroyed.
 *
 * @static
 * @constant
 */
Texture.WHITE = createWhiteTexture();
removeAllHandlers(Texture.WHITE);
removeAllHandlers(Texture.WHITE.baseTexture);